A rail car bottom outlet valve (BOV) handle can become loose for several reasons, even after it has been tightened. Some possible causes include:
1. **Vibration and Movement**: Rail cars experience significant vibration and movement during transit. Over time, this can cause screws, bolts, or other fastening mechanisms to loosen, leading to a loose handle.
2. **Wear and Tear**: Mechanical components can wear down over time. Frequent use can wear